1. Field of the Invention
This invention relates to recording and storing signals and, in particular, to recording and storing signals from multiple sources.
2. Description of Related Art
Currently, there exists a large number of analog and digital signals available for home use. Analog signals include conventional television signals that are typically sent directly to a home television receiver via cable, satellite, or terrestrial transmissions using analog standards such as NTSC, PAL, and SECAM. Other analog signals include RF signals, audio signals, and data streams. More recently, signals (both video and audio) are also being transmitted digitally, which have been encoded according to the MPEG (Moving Pictures Experts Group) standard.
Home networking allows these signals from multiple sources to be connected to and output from a single source, such as a television (monitor and speakers), so that consumers can receive a variety of entertainment and information on their television sets. However, not all signals are standardized in a common format, i.e., they are transmitted with different formats, thereby requiring different types of receivers or devices to receive and process the various signals to an appropriate output format. These devices can include set-top boxes (STBs), video cassette recorders (VCRs), satellite dishes, and cable boxes for receiving signals from transmission methods such as direct satellite service (DSS), microwave broadcast, cellular television (xe2x80x9cwireless cablexe2x80x9d), and television delivered via digital telephone phone lines. Further, as home television systems become more advanced and the number of signal sources that such systems can receive increases, situations may arise where signals from two or more sources are desired during simultaneous or overlapping time periods.
In these cases, different recording and storage devices are required for each signal source. For example, an analog video cassette recorder (VCR) can be used for recording analog video/audio signals, a tape, CD, MD, or solid state memory can be used for storing analog/digital audio and data, and a memory card and hard disk drive (HDD) can be used for storing and retrieving digital video, audio, and data. Thus, separate and differently formatted recording devices are needed to store and record one or more of the different signals simultaneously for later retrieval. As the number of different signal sources continues to increase, the number of separate recording and storage devices will also increase, thereby increasing both the size and cost of the home networking system.
Therefore, it is desirable to provide a system for simultaneously recording and storing signals from multiple sources that overcomes the disadvantages discussed above associated with conventional systems.
In accordance with an aspect of the invention, a system and method are provided which allows simultaneous signals from various sources to be processed and stored for later retrieval and playback. Analog signals and digital signals of various formats are input to a source interface. The source interface routes selected signals, via a selector device such as a remote control, to appropriate devices for processing. Analog signals are routed to an analog tuner/demodulator to demodulate the RF signals down to IF signals. The IF signals are then transmitted to a decoder for converting the IF signals to a common analog format, such as NTSC, PAL, RGB, or YUV. The analog signals are then digitized using an analog-to-digital converter. The sampling rate or frequency can be selected by the user or automatically selected based on the quality of the analog signals and the quality of the output display device. Once the analog signals have been converted to digital signals, the digital signals are sent to an encoder for time-compression (e.g., MPEG encoding) to reduce the bit rates. After encoding, the digital signals are stored in a buffer.
Digital signals already in the desired format (e.g., MPEG) are routed to a demultiplexer to separate the digital stream into individual data streams, such as video and audio. These digital streams are also stored in the buffer. Digital signals in a format different than the desired format are first converted to the desired format by a converter before being transmitted to the buffer. Once all the signals from the various sources are in a common desired digital format (e.g., MPEG), the signal streams are sent to a packetizer for processing each signal stream into packets for identification and later retrieval. Once the signals have been packetized, they are sent to a formatter, which multiplexes the signals onto a single digital transport stream. The transport stream can then be stored in a digital storage device to be accessed at a later time. Thus, signals transmitted simultaneously or during overlapping time periods from different sources can be stored and retrieved by accessing specific packets within the stored transport stream. This eliminates the need for multiple decoders to receive and decode the incoming information.